DRILLING SYSTEM, BIASING MECHANISM AND METHOD FOR DIRECTIONALLY DRILLING A BOREHOLE
A drilling system for directional drilling of a borehole includes a biasing mechanism having a pivot associated with a lower bearing assembly, an offset mechanism associated with an upper radial bearing assembly, and a toolface controller, whereby the angular relationship of a drill bit and its toolface angle may be actively managed.
This application claims the benefit and priority benefit of U.S. Provisional Patent Application Ser. No. 61/653,150, filed May 30, 2012, and entitled Drilling System, Biasing Mechanism and Method for Directionally Orienting a Borehole.
BACKGROUND OF THE INVENTION1. Field of the Disclosure
This disclosure relates generally to the field of drilling systems, biasing mechanisms for use with drilling systems, and methods for directionally orienting downhole assemblies, including directionally drilling boreholes.
2. Description of the Related Art
The following descriptions and examples are not admitted to be prior art by virtue of their inclusion within this section.
Wells, or boreholes, are generally drilled in the ground to recover natural deposits of hydrocarbons and other desirable materials trapped in geological formations in the Earth's crust. A drill bit is attached to the lower end of a drill string suspended from a drilling rig. The drill string is a long string of sections of drill pipe that are connected together end-to-end to form a long shaft for moving the drill bit into the Earth. Drilling fluid, or “mud”, is typically pumped down through the drill string to the drill bit. The drilling fluid may not only lubricate and cool the drill bit, but it may also be used to drive a mud motor.
Directional drilling is the intentional deviation of the borehole from the path it would naturally take when the borehole is drilled by advancing a drill bit into the Earth, whereby a portion of the borehole is inclined at an angle with respect to the vertical and with the inclination having a particular compass heading or azimuth. In directional assemblies, the drill bit has a “toolface” angle. The toolface angle is the relative position of the angle of the bit shaft, to which the drill bit is attached, to the high side of the borehole. This toolface angle is the offset from the high side of the borehole in which the drill bit is deviated when viewed from a plane perpendicular to the longitudinal axis of the borehole. The high side of the borehole can be determined based on the Earth's gravitational field. The Earth's magnetic field can also be used for the determination of borehole high-side. The high-side is determined with the magnetic field vector and specific understanding of the borehole's location in latitude and longitude on the Earth. As a borehole is drilled, the toolface angle determines the direction the borehole is drilled and subsequently the borehole's inclination, or the angle with respect to gravity and the borehole's azimuth, or compass heading, when viewed from above the Earth's surface.
Currently, directionally drilling of oil and gas wells is typically done with either a mud motor or with a Rotary Steerable System (“RSS”). With mud motor based directional drilling methods, the rotation of the drill string is stopped and the mud motor's orientation is accomplished by orienting the drill pipe, or drill string, from the Earth's surface to point the mud motor in a new direction typically by lifting the mud motor upwardly from the bottom of the borehole, or off-bottom, and then rotating the drill string to point the mud motor in the desired new direction. The mud motor based directional drilling system is then pushed forward without rotation of the drill pipe, which is generally referred to as a “slide”. During a slide, only the drill bit is rotating as it is driven by the mud motor. The toolface angle, or toolface, which establishes the new trajectory for the borehole to be drilled determines both the inclination, or angle with respect to gravity and the azimuth, or compass heading, at which the directional drilled borehole will be drilled. For drilling a straight borehole, the drill string is rotated from surface, subsequently rotating the mud motor and bent housing to drill forward. During such rotational drilling, the resulting borehole diameter is slightly larger than the gauge diameter of the drill bit due to the rotation of the bent housing typically used in such drilling.
An RSS uses complex, electromechanical systems that include sensors, onboard computers, and advanced control systems to continuously orient the drill bit in the desired direction, while the entire RSS and drill pipe continue to rotate.
BRIEF SUMMARYThe following presents a simplified summary of the disclosed subject matter in order to provide a basic understanding of some aspects of the subject matter disclosed herein. This summary is not an exhaustive overview of the technology disclosed herein. It is not intended to identify key or critical elements of the invention or to delineate the scope of the invention. Its sole purpose is to present some concepts in a simplified form as a prelude to the more detailed description that is discussed later.
In one illustrative embodiment, a drilling system may include a power section, a bearing section, an offset shaft, and a biasing mechanism associated with the bearing section to bias the bit shaft to be angularly displaced to permit directional drilling of a borehole. The biasing mechanism may include a pivot associated with a lower bearing assembly of the bearing section, and an offset mechanism associated with an upper radial bearing assembly of the bearing section. An offset mechanism control in the bearing section may also be provided as part of the biasing mechanism. The mud motor may not include a bent housing. The drilling system may include a toolface controller.
In another illustrative embodiment, a biasing mechanism having a bearing section, including a housing, biases an offset shaft, rotating within the housing, to be angularly displaced to permit directional orientation of a downhole assembly, such as in directional drilling of a borehole, and the biasing mechanism may include a pivot associated with a lower bearing assembly, and an offset mechanism associated with an upper radial bearing assembly. The biasing mechanism may include a toolface controller.
The present drilling system, biasing mechanism, and method for directionally drilling a borehole may be understood by reference to the following description taken in conjunction with the accompanying drawing, in which:
While certain embodiments of the present drilling system, biasing mechanism, and method for directionally drilling a borehole will be described in connection with the preferred illustrative embodiments shown herein, it will be understood that it is not intended to limit the invention to those embodiments. On the contrary, it is intended to cover all alternatives, modifications, and equivalents, as may be included within the spirit and scope of the invention as defined by the appended claims. In the drawing figures, which are not to scale, the same reference numerals are used throughout the description and in the drawing figures for components and elements having the same structure, and primed reference numerals are used for components and elements having a similar function and construction to those components and elements having the same unprimed reference numerals.
DETAILED DESCRIPTION OF THE SPECIFIC EMBODIMENTSWith reference to
Still with reference to
The bent housing section 75 permits the longitudinal axis of the housing 81 of bearing section 80 and the longitudinal axis of the bit shaft 90 to be angularly misaligned, or offset, from the axis of the drill collars 78 located above the bent housing 75.
With reference to
Bit shaft, or offset shaft, 150 has a first portion 151, which preferably includes a bit box 151′ and a bit box face, or lower-surface, 151″ at its lower end, extending outwardly from the lower end 122 of the bearing section housing 121, and a second portion 152 and a third portion 153 are disposed within the bearing section housing 121. The first portion 151 may be adapted for use with any drill bit, such as rotatable drill bit 500 (
In general, as will be hereinafter described in greater detail, the biasing mechanism 160 and offset mechanism 200 are utilized to bias the bit shaft, or offset shaft 150 to provide an axis tilt, or angular offset to the bit shaft 150 to permit the desired directional orientation of the bit shaft 150 to directionally drill a borehole. Biasing mechanism 160, such as by offset mechanism 200, generally can vary, or adjust, an angular relationship between the longitudinal axes of the housing 121 and the bit shaft 150. An offset mechanism controller 250, in general, may be provided to control the movement of the offset mechanism 200 in order to vary the angular offset, or axis tilt, for the bit shaft 150. Alternatively, some embodiments of the present mud motor, or drilling system 100, may not vary the axis tilt, or angular offset, of the bit shaft and instead may have a fixed angular offset, or axis tilt, for the bit shaft 150. Embodiments of the present mud motors, or drilling systems, 100 may include a toolface controller 300 which controls the toolface angle of a drill bit associated with the bit shaft 150. The toolface angle establishes the relative position of the angle of the bit shaft 150 to the high side of the borehole. This toolface angle is the angular offset from the high side of the borehole in which the drill bit is deviated when viewed from a plane perpendicular to the longitudinal axis of the borehole, or similarly to the longitudinal axis of the bearing section housing 121. The high side of the borehole can be determined based on the Earth's gravitational field. The Earth's magnetic field can also be used and the high side determined with the magnetic field vector and specific understanding of the latitude and longitude on the Earth. As the borehole is drilled, the toolface angle determines the direction the borehole is drilled and subsequently the borehole's inclination, or the angle with respect to gravity and the borehole's azimuth, or compass heading, when viewed from above the Earth's surface. In general, the toolface controller 300 preferably rotates the offset mechanism 200 relative to, and independent of, the housing, or bearing section housing, 121, whereby the toolface angle may be variably controlled and altered during directional drilling operations, with such variable control being independent of angular offset, or axis tilt, of the bit shaft 150. Alternatively, a toolface controller 300 may not be utilized, operated, or provided and the toolface angle remains fixed during drilling operations.
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Spherical bearing 171 includes a ball 174 matingly received within a matching spherical pocket 175 formed in the interior of the bearing section housing 121. Ball, or ball member, 174 may have its sides truncated as shown in
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The lower axial, or thrust, bearing 181′ adjacent pivot member 174″ in
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When actuation of an offset mechanism 200 of
The control of the offset mechanism controller 250 that allows the relative displacement of the components of the offset mechanism 200 can be accomplished through various mechanisms. The control of the offset mechanism controller 250 associated with the upper radial bearing assembly can be done through: surface control using relative pressure or changes in flow; surface control using changes in speed; use of downhole mechanical, electrical or electro-mechanical, hydraulic controllers known to those in the industry; use of downhole electronics and/or downhole computer control systems; use of a combination of surface control and downhole systems to provide dynamic and real time control of the downhole adjustable offset/bias; and use of downhole electronics in combination with downhole sensors to maintain toolface and offset angle, as are known in the industry. The use of downhole electronics with downhole sensor, combined with control signals from both downhole and the surface are preferred to control the downhole adjustable offset/bias.
As to the offset mechanism controller 250 to actuate the offset mechanisms 200, mechanical and electro-mechanical actuators such as motors, clutches and brakes are preferred. Mechanical actuators that can be hydraulically controlled using pumps at the surface could be utilized. With reference to
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As the ratchet pistons 252, 253 are moved axially in the direction of arrows 300 (
Dual ratchet piston actuator 251, in combination with the offset mechanisms 200 of
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The biasing mechanism 160 can be configured to create orientation in a variety of downhole assemblies for various types of drilling systems. It is currently contemplated that traditional drilling systems which use mud motors having positive displacement motors or turbine motors will be the most frequent application. However, other variations of drilling systems could also use biasing mechanism 160, such systems including orientation for laser drilling, percussion drilling, hammer drilling, cable drilling, and sonic drilling, etc.
The drilling system can be conveyed in the borehole by various well known devices including, but not limited to, wireline, slickline, drill pipe, casing, tubing and autonomous means.
The driveshaft and offset shaft, or bit shaft, of such drilling systems can be comprised of internal and/or external cross-sectional configurations including, but not limited to, circular, circular with a circular or non-circular bore, polygonal, and polygonal with a circular or non-circular bore. It is known that modifying the shape of the shafts allow for higher torque and power transmission through the shaft.
The universal joint coupling design, such as joints 77′ and 77″ shown in
The offset mechanism 250 controller may be designed for various applications. A simple fixed bend or adjustable bend can be created using a simple mechanical offset controller. It is contemplated that the system could be controlled while downhole through the use of downhole electromechanical systems and downhole electronics. Communication to these systems is contemplated through techniques known to those skilled in the art to include, but not be limited to, electromagnetic communication, wired drill pipe, communication through pressure pulses in the mud column, sound in the pipe and by radio frequency identification (RFID). It is contemplated that the offset mechanism controller 250 could communicate with other downhole systems and/or directly to the surface. As directional drilling operations proceed, if desired, the offset mechanism controller 250 may be operated to vary the offset angle, from the Earth's surface, without withdrawing housing 121 or the drill string, from the borehole and without removing axial load from the drill string.
Downhole sensors for measuring parameters internal and external to the biasing mechanism 160 may be utilized, such as inclinometers, magnetometers, gyroscopes, and/or combinations of these sensors, as well as other types of sensors known to those in the art. Measurements of external parameters include, but are not limited to: drilling parameters, such as rotation rate, inclination, azimuth, shock, vibration, temperature, pressure, etc.; and/or formation parameters, such as resistivity, naturally occurring gamma ray, pressure, density, water salinity, porosity, water volume, etc. An offset mechanism control system and/or toolface control system for use in a downhole drilling system could utilize information from such downhole sensors to modify the angular orientation or relative position of elements within the biasing mechanism 160 in response to predetermined, programmed, or real time information to achieve any desired angular displacement of offset shaft, or bit shaft, and/or relative toolface position to permit directional drilling of a borehole in a desired direction.
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On the other side of annular pivot socket member 356 is a concave spherical pivot, or bearing, surface 358 which bears, or shoulders against, a convex spherical pivot surface 359 of annular load washer 355. The other end of load washer 355 has a concave, spherical shaped pivot surface 360 which bears and shoulders against the outer convex, spherical shaped outer surface of spherical pivot member 174″. The spherical shaped convex and concave bearing, or pivot, surfaces 156, 357, 358, 359, 360 and pivot member 174″ may be provided with any suitable bearing material such as polycrystalline diamond element, or carbide elements, as previously described, and as are known within the art. Thrust bearing 350′ thus can transfer axial loads, in an on-bottom condition to the bearing housing 121 via bias housing 176″.
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Thrust bearing 370 functions as an off-bottom axial, or thrust, bearing, which transfers axial forces to the bias housing 176′″ and housing 121, when the drill bit associated with bit shaft 150 is disposed in a spaced relationship from the bottom of a borehole. Thrust bearing 350′ serves as the on-bottom thrust bearing for drilling system 100 when a drill bit associated with bit shaft 150 is in contact with the bottom of a borehole. Radial bearing 230 acts as a radial bearing support and is also part of the offset mechanism 200′ by which the bit axis offset is obtained, as previously described. Bearing 230 is offset and/or deviated from the center-line, or longitudinal, axis of the bearing housing 121 so as to force the upper end, or third portion, 153 of bit shaft 150 to the desired asymmetric, deviated and/or offset position. The bit shaft 150 remains free to rotate relative to the bearing housing 121 because the deviation created by the radial bearing 230 results in an offset axis that still passes through the center point of the bearing assembly pivot. This pivot center point is defined by the center point of the pivot spherical surfaces, and all other spherical pivot surfaces have radii origins that are collocated with the pivot center point.
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The foregoing described bearings, including axial, or thrust, bearings 350, 350′, 350″, 370, and 370′, and radial bearings 180 and 230 cooperating therewith as previously described, provide a variable offset bearing assembly associated with the offset, or bit, shaft 150 and housing 121, 176′″ that allows for, or permits, axial misalignment between the longitudinal axes of the offset shaft 150 and the housing 121, 176″, as well as manages axial and radial misalignment of the radial and thrust bearings associated with the offset shaft and housing caused by any axial or radial forces exerted upon the housing and offset shaft by drill bit 500 (
The drilling systems 100 illustrated in
With reference to the mud motor, or drilling system, 100 of
Similarly, with reference to the mud motor, or drilling system, 100 of
The offset mechanism 200 of
With reference to all of the biasing mechanisms 160, and in particular the pivot 170 of each of them as illustrated in
It should be noted that in all of the foregoing described embodiments of the present mud motors, or drilling systems, 100, as shown in
The drilling system, or mud motor, 100 as previously described is utilized to directionally drill a borehole in the following manner. The drill string is moved, such as by pushing it, until the drill bit 500 (
The drilling system, or mud motor, 100 previously described herein is utilized to directionally drill a borehole during a slide, or in sliding mode, during which time the axis tilt, a, or angular offset, e, associated with bit shaft 150, or the angular relationship between the longitudinal axes of the housing 121 and bit shaft 150 as previously described, is “actively managed”. Additionally during a slide, the toolface angle, or toolface orientation, of the drill bit associated with the bit shaft 150, may also be “actively managed”. The term “actively manage” means in this specification and its claims that the axis tilt, or angular offset, associated with bit shaft 150, or the angular relationship between the longitudinal axes of the housing 121 and bit shaft 150, may be continuously and selectively varied and controlled while the mud motor, or drilling system, 100 is in the borehole with the bit shaft 150, and its associated drill bit, rotating and drilling the borehole without rotation of the drill string or the housing 121 of bearing section 120, as previously described, without removal of the drilling system 100 from the borehole, and while maintaining WOB on the drill bit. Similarly, to “actively manage” toolface angle means in this specification and its claims that the toolface angle of drilling system, or mud motor, 100 may be continuously and selectively varied and controlled while bit shaft 150 and its associated drill bit are rotating to directionally drill the borehole, without rotation of the housing 121 of bearing section 120, without removal of the drilling system, or mud motor, 100 from the borehole. As previously described, the axis tilt, or angular offset, associated with bit shaft 150 may be continuously and selectively varied and controlled by operation of the biasing mechanism 160 previously described, including offset mechanisms 200, 200′, as well as previously described offset mechanism controllers 250 and/or actuators 251. The toolface angle may be continuously and selectively varied and controlled during drilling operations by use of toolface controller 300, as previously described.
If desired, drilling system, or mud motor, 100 may also be operated with: a fixed, non-variable, axis tilt or axis offset of bit shaft 150 and a fixed toolface angle as shown and described in connection with
When the downhole orientation of the drilling system, or mud motor, 100 is actively managed during a slide, or in the sliding drilling mode, the slide may be initiated with all WOB being applied. In certain applications, including horizontal wells with long lateral sections, the ability to transfer WOB using a traditional mud motor is impaired during sliding due to the larger static coefficients of friction. One technique to apply WOB to a drill bit is to rotate the drill pipe, or drill string, from the Earth's surface, or the drilling rig on the Earth's surface, which allows the drill pipe or drill string, to move downwardly through the borehole, thereby compressing the lower end of the drill string and placing WOB on the bit. During rotation of the drill string, the coefficient of friction is reduced and WOB can be transferred to the bit. An approach can be used with drilling system 100 to extend the length of the borehole beyond that of conventional mud motors in long laterals. The drilling system 100 is rotated from the Earth's surface, and the entire drill string is placed in compression until WOB is transferred to the bit. The downhole orientation, including offset angle and/or toolface angle, of the drilling system, or mud motor, 100 is actively managed during a slide, or in the sliding drilling mode, and the slide may be initiated with all WOB being applied. The borehole will be lengthened until the compressive forces are released and available WOB is removed from the bit. This process can be repeated to lengthen the horizontal borehole and maintain directional orientation of the borehole. With conventional mud motors, this technique does not work successfully. With conventional mud motors, the mud motor must be lifted off-bottom to orient it in the correct direction as previously described, and lifting the mud motor off-bottom removes the compressive force, or WOB, and the mud motor cannot move forward in the borehole. In contrast, the present drilling system, or mud motor, 100 described herein, can readily add the necessary WOB to the drill bit after the WOB has been drilled off, by rotation of the drill pipe, or drill string, which allows the drill pipe, or drill string, to move through the borehole, thereby compressing the lower end of the drill string and placing WOB on the drill bit associated with bit shaft 150. As the present drilling system, or mud motor, 100 does not have to be removed from the borehole to permit adjusting and varying of the axis tilt, or angular offset, as well as to permit adjusting and varying toolface angle, the drilling system 100 may be rotated for a short period of time from the Earth's surface, such as by rotation of the drill pipe, or drill string, and housing 121 associated therewith, whereby WOB may be applied to the drill bit associated with bit shaft 150, which continues drilling operations in a subsequent slide, during which toolface angle and/or axis tilt, or angular offset may be selectively varied and adjusted to permit drilling system 100 to continue drilling operations in the desired direction and orientation. Rotation of the drill string allows drilling system 100 to put WOB onto the bit associated with bit shaft 150 and once the WOB is on the bit associated with bit shaft 150, the drill string is in compression. With the drill string in compression while sliding, and the toolface angle and/or axis tilt, or angular offset, being continuously and selectively adjusted or varied, as previously described, the path, or trajectory of the borehole can be modified or changed as necessary to correct for any errors in direction. The foregoing drilling method, which includes a short rotation period for the drill string from the Earth's surface, can be repeated as necessary to continue to apply WOE to the drill bit after the WOB has been drilled off.
In connection with the foregoing described methods and the phrases “without rotation of the drill pipe, or drill string”, “without rotation of the housing 121”, “without rotation of the drill string or the housing 121”, and similar phrases, such phrases are defined to mean in this specification and its claims that the drill string, or drill pipe, and housing 121 are not intentionally rotated from the Earth's surface as by a drilling rig on the Earth's surface engaging and rotating the upper end of the drill string at the Earth's surface, as is conventional in the art. In this regard, if a drill string is rotated in the previously described method to add WOB to the drill bit 500 of the present drilling system 100, upon ceasing the rotation of the drill string from the Earth's surface, there may be some torsional wind up forces stored in the drill string, which may be thereafter released, once the WOB has been drilled off, which may cause some subsequent, undesired, unintended rotation of the drill string and housing. To the extent the drill string and housing 121 of the present drilling system may experience such subsequent, undesired, unintended rotation, such rotation is excluded from the foregoing definition of the foregoing phrases in the specification and claims. In this regard, an advantage of the present drilling system 100 is that during unintended rotation, during a slide, or in sliding mode, drilling system 100 can compensate for the unwinding, or unintended rotation, of the drill string and maintain a desired toolface angle, by actively managing toolface angle.
Specific embodiments of the present drilling system, biasing mechanism, and method for directionally drilling a borehole have been described and illustrated. It will be understood to those skilled in the art that changes and modifications may be made without departing from the spirit and scope of the inventions defined by the appended claims.
Claims
1. A biasing mechanism comprising:
- a bearing section, including a housing having a lower end and a longitudinal axis, including a lower bearing assembly and an upper radial bearing assembly within the housing, the housing;
- an offset shaft, having a longitudinal axis, an upper end, and a lower end, independently rotatable within the housing, the offset shaft having a first portion, including the lower end of the offset shaft, extending outwardly from the lower end of the bearing section housing, a second portion disposed within the bearing section housing associated with the lower bearing assembly, and a third portion disposed within the bearing section housing associated with the upper radial bearing assembly; and
- a biasing assembly associated with the bearing section to bias the offset shaft to be angularly displaced to permit directional orientation of a downhole assembly, the biasing assembly including: a pivot having a mid-point, associated with the lower bearing assembly of the bearing section; and an offset mechanism associated with the upper radial bearing assembly of the bearing section, which can selectively vary an angular relationship between the longitudinal axes of the housing and the offset shaft.
2. The biasing mechanism of claim 1, wherein the housing is non-sealed to permit a drilling fluid to lubricate the lower bearing assembly and the upper radial bearing assembly.
3. The biasing mechanism of claim 1, wherein the lower end of the offset shaft is disposed a distance from the mid-point of the pivot which is less than 36 inches.
4. The biasing mechanism of claim 1, wherein the pivot of the lower bearing assembly is a spherical bearing, through which passes the second portion of the offset shaft.
5. The biasing mechanism of claim 4, wherein the spherical bearing includes a ball and a mating pocket which receives the ball.
6. The biasing mechanism of claim 4, wherein the spherical bearing is a universal joint knuckle.
7. The biasing mechanism of claim 4, including at least one thrust bearing and at least one radial bearing associated with the lower bearing assembly.
8. The biasing mechanism of claim 7, wherein the spherical bearing of the pivot also acts as the at least one thrust bearing.
9. The biasing mechanism of claim 8, wherein the at least one radial bearing is disposed within the spherical bearing.
10. The biasing mechanism of claim 5, wherein the lower bearing assembly includes upper and lower thrust bearings and upper and lower radial bearings.
11. The biasing mechanism of claim 10, wherein the ball of the spherical bearing is truncated and the lower radial bearing is disposed within the ball and adjacent the second portion of the offset shaft.
12. The biasing mechanism of claim 1, wherein the upper radial bearing assembly includes at least one radial bearing, and the offset mechanism includes first and second counter-rotating eccentric cylinders.
13. The biasing mechanism of claim 12, wherein the at least one radial bearing is associated with an outer wall surface of the upper portion of the offset shaft; the first and second counter-rotating, eccentric cylinders each have an inner bore; the inner bore of the second counter-rotating eccentric cylinder is associated with the at least one radial bearing; and the second counter-rotating eccentric cylinder is disposed within the inner bore of the first counter-rotating eccentric cylinder.
14. The biasing mechanism of claim 13, wherein each of the first and second counter-rotating, eccentric cylinders have longitudinal axes and the longitudinal axes are parallel to each other.
15. The biasing mechanism of claim 13, wherein each of the first and second counter-rotating, eccentric cylinders have longitudinal axes and the longitudinal axes are not parallel to each other.
16. The biasing mechanism of claim 1, wherein the upper radial bearing assembly includes at least one radial bearing, and the offset mechanism includes at least one ramp member which cooperates with at least one mating support member to permit relative motion between the at least one ramp member and the at least one mating support member
17. The biasing mechanism of claim 16, wherein the at least one ramp member is a mandrel having a sloping cylindrical outer wall surface associated with the third portion of the offset shaft, and the at least one mating support member is a ring member having a mating bore for receipt of the sloping cylindrical outer wall surface of the mandrel.
18. The biasing mechanism of claim 12, including an offset mechanism controller, and the offset mechanism controller is a dual ratchet piston actuator which cooperates with the first and second counter-rotating eccentric cylinders, whereby movement of the dual ratchet piston actuator causes rotation of the first and second counter-rotating eccentric cylinders.
19. The biasing mechanism of claim 18, including at least one spring associated with the dual ratchet piston actuator.
20. The biasing mechanism of claim 16, including an offset mechanism controller, and the offset mechanism controller is a ratchet piston actuator associated with the at least one mating support member, whereby movement of the ratchet piston actuator causes relative motion between the at least one ramp member and the at least one mating support member.
21. The biasing mechanism of claim 20, including at least one spring associated with the ratchet piston actuator.
22. The biasing mechanism of claim 1, wherein the offset mechanism is fixed in a static position by an offset mechanism controller.
23. The biasing mechanism of claim 1, including an offset mechanism controller, and the offset mechanism can be adjusted while downhole in a borehole using the offset mechanism controller.
24. The biasing mechanism of claim 1, including an offset mechanism controller, and the offset mechanism controller includes downhole electronics and sensors for sensing drilling and formation parameters.
25. The biasing mechanism of claim 24, wherein the offset mechanism controller uses feedback from downhole electronics and sensors to modify the elements within the biasing mechanism.
26. The biasing mechanism of claim 24, wherein the offset mechanism controller uses downhole electronics and sensors to communicate to other downhole systems or directly to the surface.
27. The biasing mechanism of claim 1, wherein the offset mechanism can be adjusted from an upper end of a borehole.
28. The biasing mechanism of claim 1, wherein the upper radial bearing assembly includes at least one radial bearing, and the offset mechanism includes a single rotatable eccentric cylinder.
29. The biasing mechanism of claim 28, wherein the at least one radial bearing is associated with an outer wall surface of the third portion of the offset shaft; the rotatable eccentric cylinder has an inner bore associated with the at least one radial bearing.
30. The biasing mechanism of claim 28, including an offset mechanism controller, and the offset mechanism controller is a ratchet piston actuator which cooperates with the rotatable eccentric cylinder, whereby movement of the ratchet piston actuator causes rotation of the eccentric cylinder.
31. The biasing mechanism of claim 1, including a toolface controller which can selectively vary a toolface angle of a drill bit associated with the bit shaft.
32. The biasing mechanism of claim 31, wherein the upper radial bearing assembly includes at least one radial bearing, and the offset mechanism includes first and second counter-rotating eccentric cylinders.
33. The biasing mechanism of claim 32, including an offset mechanism controller wherein the two eccentric cylinders are rotatably disposed in a first fixed angular relationship with respect to each other by the offset mechanism controller, and the toolface controller rotates the two eccentric cylinders in the first fixed angular relationship with respect to the housing to selectively vary the toolface angle of the drill bit.
34. The biasing mechanism of claim 33, including a locking device wherein the toolface controller is secured and fixed within the housing and the toolface angle may not be varied.
35. The biasing mechanism of claim 31, wherein the upper radial bearing assembly includes at least one radial bearing, and the offset mechanism includes a single rotatable eccentric cylinder.
36. The biasing mechanism of claim 35, wherein the single eccentric cylinder is rotatably disposed in a first fixed angular relationship with respect to the housing and the toolface controller rotates the single eccentric cylinder in the first fixed angular relationship to the housing to selectively vary the toolface angle of the drill bit.
37. The biasing mechanism of claim 36, including a locking device wherein the toolface controller is secured and fixed within the housing and the toolface angle may not be varied.
38. The biasing mechanism of claim 31, wherein the toolface controller includes downhole electronics and sensors for sensing drilling and formation parameters.
39. The biasing mechanism of claim 31, wherein the toolface controller uses feedback from downhole electronics and sensors to modify the elements within the biasing mechanism.
40. The biasing mechanism of claim 31, wherein the toolface controller uses downhole electronics and sensors to communicate to other downhole systems or directly to the surface.
41. The biasing mechanism of claim 31, wherein the toolface controller can be adjusted from an upper end of a borehole.
42. A drilling system comprising:
- a power section
- a bearing section, including a housing having a lower end and a longitudinal axis, including a lower bearing assembly and an upper radial bearing assembly within the housing, the housing; assembly and the upper radial bearing assembly
- an offset shaft, having a longitudinal axis, an upper end, and a lower end, independently rotatable within the housing, the offset shaft having a first portion, including the lower end of the offset shaft, extending outwardly from the lower end of the bearing section housing, a second portion disposed within the bearing section housing associated with the lower bearing assembly, and a third portion disposed within the bearing section housing associated with the upper radial bearing assembly; and
- a biasing assembly associated with the bearing section to bias the offset shaft to be angularly displaced to permit directional orientation of a downhole assembly, the biasing assembly including: a pivot having a mid-point, associated with the lower bearing assembly of the bearing section; and an offset mechanism associated with the upper radial bearing assembly of the bearing section, which can selectively vary an angular relationship between the longitudinal axes of the housing and the offset shaft.
43. The drilling system of claim 42, wherein the housing is non-sealed to permit a drilling fluid to lubricate the lower bearing assembly and the upper radial bearing assembly.
44. The drilling system of claim 42, wherein the lower end of the offset shaft is disposed a distance from the mid-point of the pivot which is less than 36 inches.
45. The drilling system of claim 42, wherein the drilling system does not include a bent housing.
46. The drilling system of claim 42, wherein the drilling system includes a bent housing.
47. The drilling system of claim 42, wherein the power section is a hydraulic motor rotating power section.
48. The drilling system of claim 42, wherein the power section is a positive displacement motor.
49. The drilling system of claim 42, wherein the power section is a fluidic turbine.
50. The drilling system of claim 42, wherein the power section is an electric motor.
51. The drilling system of claim 42, wherein the offset shaft is a bit shaft and the downhole assembly is a drill bit.
52. The drilling system of claim 42, wherein the pivot of the lower bearing assembly is a spherical bearing, through which passes the second portion of the offset shaft.
53. The drilling system of claim 52, wherein the spherical bearing includes a ball and a mating pocket which receives the ball.
54. The drilling system of claim 52, wherein the spherical bearing is a universal-joint knuckle.
55. The drilling system of claim 52, including at least one thrust bearing and at least one radial bearing associated with the lower bearing assembly.
56. The drilling system of claim 55, wherein the spherical bearing of the pivot also acts as the at least one thrust bearing.
57. The drilling system of claim 56, wherein the at least one radial bearing is disposed within the spherical bearing.
58. The drilling system of claim 53, wherein the lower bearing assembly includes upper and lower thrust bearings and upper and lower radial bearings.
59. The drilling system of claim 58, wherein the ball of the spherical bearing is truncated and the lower radial bearing is disposed within the ball and adjacent the second portion of the offset shaft.
60. The drilling system of claim 42, wherein the upper radial bearing assembly includes at least one radial bearing, and the offset mechanism includes first and second counter-rotating eccentric cylinders.
61. The drilling system of claim 60, wherein the at least one radial bearing is associated with an outer wall surface of the upper portion of the offset shaft; the first and second counter-rotating, eccentric cylinders each have an inner bore; the inner bore of the second counter-rotating eccentric cylinder is associated with the at least one radial bearing; and the second counter-rotating eccentric cylinder is disposed within the inner bore of the first counter-rotating eccentric cylinder.
62. The drilling system of claim 61, wherein each of the first and second counter-rotating, eccentric cylinders have longitudinal axes and the longitudinal axes are parallel to each other.
63. The drilling system of claim 61, wherein each of the first and second counter-rotating, eccentric cylinders have longitudinal axes and the longitudinal axes are not parallel to each other.
64. The drilling system of claim 42, wherein the upper radial bearing assembly includes at least one radial bearing, and the offset mechanism includes at least one ramp member which cooperates with at least one mating support member to permit relative motion between the at least one ramp member and the at least one mating support member
65. The drilling system of claim 64, wherein the at least one ramp member is a mandrel having a sloping cylindrical outer wall surface associated with the third portion of the offset shaft, and the at least one mating support member is a ring member having a mating bore for receipt of the sloping cylindrical outer wall surface of the mandrel.
66. The drilling system of claim 60, including an offset mechanism controller, and the offset mechanism controller is a dual ratchet piston actuator which cooperates with the first and second counter-rotating eccentric cylinders, whereby movement of the dual ratchet piston actuator causes rotation of the first and second counter-rotating eccentric cylinders.
67. The drilling system of claim 66, including at least one spring associated with the dual ratchet piston actuator.
68. The drilling system of claim 64, including an offset mechanism controller, and the offset mechanism controller is a ratchet piston actuator associated with the at least one mating support member, whereby movement of the ratchet piston actuator causes relative motion between the at least one ramp member and the at least one mating support member.
69. The drilling system of claim 68, including at least one spring associated with the ratchet piston actuator.
70. The drilling system of claim 42, wherein the offset mechanism is fixed in a static position by an offset mechanism controller.
71. The drilling system of claim 42, including an offset mechanism controller, and the offset mechanism can be adjusted while downhole in a borehole using the offset mechanism controller.
72. The drilling system of claim 42, including an offset mechanism controller, and the offset mechanism controller includes downhole electronics and sensors for sensing drilling and formation parameters.
73. The drilling system of claim 72, wherein the offset mechanism controller uses feedback from downhole electronics and sensors to modify the elements within the biasing mechanism.
74. The drilling system of claim 72, wherein the offset mechanism controller uses downhole electronics and sensors to communicate to other downhole systems or directly to the surface.
75. The drilling system of claim 42, wherein the offset mechanism can be adjusted from an upper end of a borehole.
76. The drilling system of claim 42, wherein the upper radial bearing assembly includes at least one radial bearing, and the offset mechanism includes a single rotatable eccentric cylinder.
77. The drilling system of claim 76, wherein the at least one radial bearing is associated with an outer wall surface of the third portion of the offset shaft; the rotatable eccentric cylinder has an inner bore associated with the at least one radial bearing.
78. The drilling system of claim 76, including an offset mechanism controller, and the offset mechanism controller is a ratchet piston actuator which cooperates with the rotatable eccentric cylinder, whereby movement of the ratchet piston actuator causes rotation of the eccentric cylinder.
79. The drilling system of claim 42, including a toolface controller which can selectively vary a toolface angle of a drill bit associated with the bit shaft.
80. The drilling system of claim 79, wherein the upper radial bearing assembly includes at least one radial bearing, and the offset mechanism includes first and second counter-rotating eccentric cylinders.
81. The drilling system of claim 80, including an offset mechanism controller wherein the two eccentric cylinders are rotatably disposed in a first fixed angular relationship with respect to each other by the offset mechanism controller, and the toolface controller rotates the two eccentric cylinders in the first fixed angular relationship with respect to the housing to selectively vary the toolface angle of the drill bit.
82. The drilling system of claim 81, including a locking device wherein the toolface controller is secured and fixed within the housing and the toolface angle may not be varied.
83. The drilling system of claim 79, wherein the upper radial bearing assembly includes at least one radial bearing, and the offset mechanism includes a single rotatable eccentric cylinder.
84. The drilling system of claim 83, wherein the single eccentric cylinder is rotatably disposed in a first fixed angular relationship with respect to the housing and the toolface controller rotates the single eccentric cylinder in the first fixed angular relationship to the housing to selectively vary the toolface angle of the drill bit.
85. The drilling system of claim 84, including a locking device wherein the toolface controller is secured and fixed within the housing and the toolface angle may not be varied.
86. A variable offset bearing assembly, associated with an offset shaft, having a longitudinal axis, disposed with a housing, having a longitudinal axis, comprising:
- a radial bearing associated with the offset shaft;
- a thrust bearing associated with the offset shaft;
- the radial bearing and thrust bearing permit axial misalignment between the longitudinal axes of the offset shaft and the housing; and
- the thrust bearing and radial bearing manage axial and radial misalignment of the radial bearing and thrust bearing within the housing, caused by an axial or radial force exerted upon the housing and offset shaft.
87. A method for directionally drilling a portion of a borehole, comprising:
- utilizing a drilling system associated with a drill string, the drilling system, including: a bearing section having a housing having a lower end, a longitudinal axis, and an upper bearing assembly and a lower bearing assembly disposed within the housing; an offset shaft, having a lower end and a longitudinal axis, independently rotatable within the housing and a drill bit associated with the lower end of the offset shaft; and the upper and lower bearing assemblies each including a radial bearing and a thrust bearing and provide a variable offset bearing assembly;
- moving the drill string until the drill bit of the drilling system contacts a bottom of the borehole;
- rotating the offset shaft and drill bit with respect to the housing, while not rotating the drill string and the housing, to drill the portion of the borehole; and
- while the drill bit is in the borehole drilling the portion of the borehole, permitting axial misalignment between the longitudinal axes of the offset shaft and the housing and managing axial and radial misalignment of the radial and thrust bearings within the housing caused by an axial or a radial force exerted upon the housing and offset shaft.
88. A method for directionally drilling a portion of a borehole, comprising:
- utilizing a drilling system associated with a drill string, the drilling system, including: a bearing section having a housing having a lower end, a longitudinal axis, and an upper bearing assembly and a lower bearing assembly disposed within the housing; an offset shaft, having a lower end and a longitudinal axis, independently rotatable within the housing and a drill bit associated with the lower end of the offset shaft; and a biasing mechanism associated with the upper bearing assembly in the bearing section;
- moving the drill string until the drill bit of the drilling system contacts a bottom of the borehole;
- rotating the offset shaft and drill bit with respect to the housing, while not rotating the drill string and the housing, to drill the portion of the borehole; and
- while the drill bit is in the borehole drilling the portion of the borehole, operating the biasing mechanism to actively manage an angular relationship between the longitudinal axes of the housing and the offset shaft.
89. The method of claim 88, including lubricating the bearing assemblies with a drilling fluid.
90. The method of claim 88, wherein the biasing mechanism of the drilling system includes a pivot having a mid-point associated with the lower bearing assembly in the housing, and disposing the lower end of the offset shaft a distance from the mid-point of the pivot which is less than 36 inches.
91. The method of claim 88, wherein the drilling system includes a toolface controller, and while the drill bit is in the borehole drilling the portion of the borehole, operating the toolface controller to actively manage a toolface angle of the drill bit.
92. The method of claim 88, wherein the drilling system includes a toolface controller, and after the portion of the borehole has been drilled while not rotating the drill string and the housing, rotating the drill string to cause the drill string to be in compression while the drill bit contacts the bottom of the borehole; rotating the offset shaft and drill bit with respect to the housing, while not rotating the drill string and the housing, to drill an additional portion of the borehole; and while the drill bit is in the borehole drilling the additional portion of the borehole, operating the toolface controller to actively manage a toolface angle of the drill bit.
93. The method of claim 92, wherein the biasing mechanism of the drilling system includes an offset mechanism, and rotating the offset mechanism with the toolface controller to actively manage the toolface of the drill bit.
94. The method of claim 92, including while the drill bit is in the borehole drilling the additional portion of the borehole, operating the biasing mechanism to actively manage the angular relationship between the longitudinal axes of the housing and the offset shaft.
95. A method for directionally drilling a portion of a borehole, comprising:
- utilizing a drilling system associated with a drill string, the drilling system, including: a bearing section having a non-sealed housing having a lower end, a longitudinal axis, and an upper bearing assembly and a lower bearing assembly disposed within the housing; an offset shaft, having a lower end and a longitudinal axis, independently rotatable within the housing and a drill bit associated with the lower end of the offset shaft; a biasing mechanism associated with upper bearing assembly in the bearing section including an offset mechanism; and a toolface controller;
- moving the drill string until the drill bit of the drilling system contacts a bottom of the borehole;
- rotating the offset shaft and drill bit with respect to the housing, while not rotating the drill string and the housing, to drill the portion of the borehole; and
- while the drill bit is in the borehole drilling the portion of the borehole, operating the biasing mechanism to actively manage an angular relationship between the longitudinal axes of the housing and the offset shaft, and operating the toolface controller to actively manage a toolface angle of the drill bit.
96. The method of claim 95, including lubricating the bearing assemblies with a drilling fluid.
97. The method of claim 95, wherein the biasing mechanism of the drilling system includes a pivot having a mid-point associated with the lower bearing assembly in the housing, and disposing the lower end of the offset shaft a distance from the mid-point of the pivot which is less than 36 inches.
98. The method of claim 95, wherein after the portion of the borehole has been drilled while not rotating the drill string and the housing, rotating the drill string to cause the drill string to be in compression while the drill bit contacts the bottom of the borehole; rotating the offset shaft and drill bit with respect to the housing, while not rotating the drill string and the housing, to drill an additional portion of the borehole; and while the drill bit is in the borehole drilling the additional portion of the borehole, operating the toolface controller to actively manage the toolface angle of the drill bit.
99. A method for directionally drilling a portion of a borehole, comprising:
- utilizing a drilling system associated with a drill string, the drilling system, including: a bearing section having a housing having a lower end, a longitudinal axis, and an upper bearing assembly and a lower bearing assembly disposed within the housing; an offset shaft, having a lower end and a longitudinal axis, independently rotatable within the housing and a drill bit associated with the lower end of the offset shaft; and a toolface controller;
- moving the drill string until the drill bit of the drilling system contacts a bottom of the borehole;
- rotating the offset shaft and drill bit with respect to the housing, while not rotating the drill string and the housing, to drill the portion of the borehole; and
- while the drill bit is in the borehole drilling the portion of the borehole, operating the toolface controller to actively manage a toolface angle of the drill bit.
100. The method of claim 99, including lubricating the bearing assemblies with a drilling fluid.
101. The method of claim 99, wherein the drilling system includes a biasing mechanism having a pivot having a mid-point associated with the lower bearing assembly in the housing, and disposing the lower end of the offset shaft a distance from the mid-point of the pivot which is less than 36 inches.
102. The method of claim 99, wherein the drilling system includes a biasing mechanism, and while the drill bit is in the borehole drilling the portion of the borehole, operating the biasing mechanism to actively manage an angular relationship between the longitudinal axes of the housing and the offset shaft.
103. The method of claim 99, wherein the drilling system includes a biasing mechanism having an offset mechanism, and the offset mechanism is selectively operated at an upper end of the borehole to fix an angular relationship between the longitudinal axis of the offset shaft and the housing.
104. The method of claim 99, wherein after the portion of the borehole has been drilled while not rotating the drill string and the housing, rotating the drill string to cause the drill string to be in compression while the drill bit contacts the bottom of the borehole; rotating the offset shaft and drill bit with respect to the housing, while not rotating the drill string and the housing, to drill an additional portion of the borehole; and while the drill bit is in the borehole drilling the additional portion of the borehole, operating the toolface controller to actively manage the toolface angle of the drill bit.
105. The method of claim 104, wherein the drilling system includes a biasing mechanism which includes an offset mechanism, and rotating the offset mechanism with the toolface controller to actively manage the toolface of the drill bit.
106. The method of claim 104, wherein the drilling system includes a biasing mechanism, and while the drill bit is in the borehole drilling the additional portion of the borehole, operating the biasing mechanism to actively manage an angular relationship between the longitudinal axes of the housing and the offset shaft.
107. A method for directionally drilling a portion of a borehole, comprising:
- utilizing a drilling system associated with a drill string and a drill bit;
- rotating the drill string and placing an axial load on the drill string causing the drill string to move into compression; and
- stopping rotation of the drill string and with the drill string in compression, drilling a portion of the portion of the borehole while actively managing a toolface angle of the drill bit.
Type: Application
Filed: Mar 15, 2013
Publication Date: Dec 5, 2013
Patent Grant number: 9556678
Applicant: TELLUS OILFIELD, INC. (Houston, TX)
Inventors: Stuart Schaaf (Sugar Land, TX), Marcus D. Wernig (Orange, TX)
Application Number: 13/837,665
International Classification: E21B 7/06 (20060101); E21B 44/00 (20060101);